diff --git a/poetry.lock b/poetry.lock
index e96c2b4b..6e7f87db 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -708,7 +708,7 @@ python-versions = "*"
 
 [[package]]
 name = "sphinx"
-version = "3.5.2"
+version = "3.5.4"
 description = "Python documentation generator"
 category = "dev"
 optional = false
@@ -718,7 +718,7 @@ python-versions = ">=3.5"
 alabaster = ">=0.7,<0.8"
 babel = ">=1.3"
 colorama = {version = ">=0.3.5", markers = "sys_platform == \"win32\""}
-docutils = ">=0.12"
+docutils = ">=0.12,<0.17"
 imagesize = "*"
 Jinja2 = ">=2.3"
 packaging = "*"
@@ -961,7 +961,7 @@ testing = ["pytest (>=3.5,!=3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7.0"
-content-hash = "caed8593fd4b5caa966794a9cd62ce7b8b60ded2ce65aafe42513f9e28b9efe0"
+content-hash = "0e29f828b52ce7ed865fb99170d37ceb3d9fb3508457578564c0f686961f5541"
 
 [metadata.files]
 alabaster = [
@@ -1425,8 +1425,8 @@ snowballstemmer = [
     {file = "snowballstemmer-2.0.0.tar.gz", hash = "sha256:df3bac3df4c2c01363f3dd2cfa78cce2840a79b9f1c2d2de9ce8d31683992f52"},
 ]
 sphinx = [
-    {file = "Sphinx-3.5.2-py3-none-any.whl", hash = "sha256:ef64a814576f46ec7de06adf11b433a0d6049be007fefe7fd0d183d28b581fac"},
-    {file = "Sphinx-3.5.2.tar.gz", hash = "sha256:672cfcc24b6b69235c97c750cb190a44ecd72696b4452acaf75c2d9cc78ca5ff"},
+    {file = "Sphinx-3.5.4-py3-none-any.whl", hash = "sha256:2320d4e994a191f4b4be27da514e46b3d6b420f2ff895d064f52415d342461e8"},
+    {file = "Sphinx-3.5.4.tar.gz", hash = "sha256:19010b7b9fa0dc7756a6e105b2aacd3a80f798af3c25c273be64d7beeb482cb1"},
 ]
 sphinx-autobuild = [
     {file = "sphinx-autobuild-2021.3.14.tar.gz", hash = "sha256:de1ca3b66e271d2b5b5140c35034c89e47f263f2cd5db302c9217065f7443f05"},
diff --git a/pyproject.toml b/pyproject.toml
index f1825b2b..86f3e4c6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,7 +41,7 @@ safety = "^1.10.3"
 mypy = "^0.812"
 typeguard = "^2.11.1"
 xdoctest = {extras = ["colors"], version = "^0.15.0"}
-sphinx = "^3.5.2"
+sphinx = "^3.5.4"
 sphinx-autobuild = "^2021.3.14"
 pre-commit = "^2.11.1"
 flake8 = "^3.9.0"